Question: Tiffany is 4 times as old as Brandon and is also 18 years older than Brandon. How old is Brandon?
Answer: We can use the given information to write down two equations that describe the ages of Tiffany and Brandon. Let Tiffany's current age be $t$ and Brandon's current age be $b$ $t = 4b$ $t = b + 18$ Now we have two independent equations, and we can solve for our two unknowns. Since we are looking for $b$ , and both of our equations have $t$ alone on one side, this is a convenient time to use elimination. Subtracting the second equation from the first equation, we get: $0 =$ $4b$ $-$ $ (b + 18)$ which combines the information about $b$ from both of our original equations. Solving for $b$ , we get: $3 b = 18$ $b = 6$.